The conventional method of filling a resin into a reflector housing for making an LED digital display has problems in evacuating air completely from corners of the reflector housing due to factors such as the shape of the reflector housing. As a consequence, air bubbles are formed and trapped in the resin in the reflector housing. Therefore, after injection of the resin, the reflector housing is required to be placed into a vacuum chamber to remove the air bubbles from the resin.
However, the air bubbles often burst when they reach the top surface of the resin (such as epoxy resin) during the vacuuming operation, which results in overflow of the resin from the reflector housing. The overflow of the resin adheres to the outer surface of the reflector housing, and is required to be removed (cleaned) manually. In addition, re-examination of whether there are any air bubbles remaining in the resin and further removal of the remaining air bubbles from the resin may be needed to ensure that the resin is free of the air bubbles. In other words, having air bubbles trapped in the resin complicates the conventional method in that an additional procedure is required to solve this problem. Therefore, there is a need for a method that can prevent air bubbles from being formed in the resin.